Customer owned private branch exchange (PBX) systems are in widespread use. PBX systems adequately serve a large number of stations or telephone extensions in a single location. Frequently, however, customers have multiple locations, each having a PBX system or hybrid key system associated with it. These systems typically are controlled by computer-telephone integration (CTI) processors into various types of networks.
An early communications switching concept was disclosed in U.S. Pat. No. 4,527,012 to allow telephone call processing to be carried out by a host computer connected to a telephone system. The host computer viewed the telephone system as a peripheral device. The host computer then controlled the switching system with a series of high level commands exchanged between the switching system and the host computer. The commands were referenced to physical system ports to control the operation of those ports directly, based on the current call processing state. The connection of the host computer to the telephone system was accomplished by using a serial port (such as the RS-232 port). The system of this patent, however, and systems similar to it, are not inherently capable of connections or control using a computer network like TCP/IP because of the electrical network interface limitations of serial ports. In addition, computer programs of the type disclosed in the ""012 patent must be aware of each equipped physical system port, and maintain a separate cross reference to correlate ports functionally to the assigned extension numbers, trunk numbers and so forth.
A different approach is disclosed in U.S. Pat. No. 4,653,085. In the system of this patent, computer telephony is implemented by attaching an adjunct processor to an associated telephone system port and sending control information for calls requiring additional call processing using a data exchange with the adjunct computer to simulate the actions of a connected station. The system of this patent requires all telephone calls, which are to be handled according to the stored program in the adjunct processor, to be transmitted by the telephone system to the port associated with that adjunct processor. The adjunct processor then sends direct commands back to the telephone system indicating the disposition of the call by directly sending a command to the port being served. Consequently, the adjunct computer simulates the behavior of a human operator. This system is limited by the volume of traffic which can be processed by a single operator (adjunct computer), and therefore it is not suitable for system-wide call handling tasks without terminating multiple ports to simulate the activities of multiple human operators.
U.S. Pat. No. 5,414,762 is directed to a system for providing computer control to a variety of PBX systems. In the system of this patent, a controller is used to allow one or more computers from a group of computer clients to send commands to a PBX by way of a server computer, and also to receive status information from the connected PBX. A converter which is specific to a particular PBX manufacturer is provided to allow the brand of PBX to be changed without having to modify the communications protocol, and therefore, the application software, that the computer client contains. The primary focus of this system is to allow the same client software to control a variety of PBX platforms. The system of the patent, however, provides no functional support for an application software developer to address the needs of multiple PBX systems, or for expanded networks of PBX systems in multiple locations. In either of these cases, the application software must be enhanced to allow it to be aware of, and to properly control, multiple PBX nodes. Because the application software resides at the client level, it can only control one call per work station and cannot address the needs of the entire system. An approach to resolve problems associated with routing calls to geographically distributed PBX nodes is disclosed in U.S. Pat. Nos. 5,546,452 and 5,848,143. The systems of these patents use a central controller with global authority to allow resident software to route calls appropriately to agents who are connected at various locations within the PBX network. The systems disclosed in these patents require the central processor to be equipped with routing and management software specifically designed for the expected call processing activity. These systems do not facilitate the transposition of a generic computer telephony application from a single PBX to networked PBX environment, and must take full control of the PBX network by correlating the identities of logged-in agents with a physical node and port locations in the PBX. As a consequence, the approach used in the systems of these patents requires a facility which must undergo continuous parallel maintenance to keep up with PBX user changes.
U.S. Pat. No. 5,479,487 discloses a system for allowing a centrally located scripting language to control a call as it passes between functional partitions within a call center system. The system creates a scripted development environment for distributed call processing products; but it does not address cases where there is a distributed network of PBX systems which require computer telephony control from some centralized application.
U.S. Pat. No. 6,011,844 is directed to a system for saving long distance toll charges. The system uses interconnected computer gateways to coordinate the switching of calls between network call centers. Each of these call centers receives telephone traffic according to methods designed to provide the lowest cost handling of each call, and only xe2x80x9cbridges inxe2x80x9d calls over the long distance network when necessary. The system of this patent is narrowly focused on reducing call traffic over the long distance network which may be handled in a local call center. The system is not capable of centralized consolidation of events arriving from different connected PBX nodes.
With the advent of intelligent networks within the public telephone system, U.S. Pat. No. 6,094,479 is directed to a solution which allows for the public network service control element to link with a PBX located within a customer""s private network by using a gateway between the private and public network segments. The gateway, however, is limited in its functionality because it simply provides a standard means to link between two networks, and does not address the problems created when a customer makes the transition from single to multiple PBX nodes within a private network.
U.S. Pat. No. 6,181,788 is directed to a system for achieving uniform control of mixed platforms in telephony. Not all PBX manufacturers use the same protocols to implement computer-telephone integration (CTI) interfaces to a control computer. This patent is directed to a solution to solve software interface problems for customers who have a network of mixed types of PBX systems. The solution proposed in the ""788 patent is to use the CTI processors to convert the protocols from each PBX and then network together the CTI processors by way of a peer-to-peer network. Each CTI processor contains its own software with some form of messaging used to loosely link the various systems at each site. This patent is directed to the problem of mixed or different PBX system types. The patent does not address the problem of system scaling (that is, adding additional PBX""s to a customer""s system), and control of networked systems using a common software application.
It is desirable to enhance the CTI functionality of a PBX network having multiple nodes by combining bi-directional data from remote telephone switching nodes (different PBX systems) into one data stream to simplify the control of the remote system.
It is an object of this invention to provide an improved system and method for serving multiple telephone switches.
It is another object of this invention to provide an improved method and system for a private branch exchange (PBX) telephone system network.
It is an additional object of this invention to provide an improved interface network linking a plurality of PBX systems over a wide area network.
It is a further object of this invention to provide an improved system and method employing computer telephony interface (CT) for a private branch exchange (PBX) telephone system network using a common software application for linking each of the PBX exchanges together in a transparent manner to users at any of the exchanges.
In accordance with a preferred embodiment of the invention, a computer telephony interface CT) for a private branch exchange (PBX) telephone system network utilizes a gateway processing system located on an adjacent computer. Each of the PBX systems has a unique address; and they are linked together through a wide area network (WAN), local area network (LAN), or the Internet to the Gateway processing system. The processing system includes translation tables for the addresses, as well as individual station extensions; so that calls originating from any one of the PBX systems on the network and directed to a station on any of the other PBX systems on the network pass their event (call progress) notification through the gateway where it is translated and directly sent to all users (applications) that requested the information in a manner which is transparent to the users of the system. Thus, the users are not aware that more than one PBX system is involved in the call event. The system also allows for changing the data in the translation table to allow relocation of a device associated with a particular extension number to any one of the PBX systems in the network without requiring individual programming at that, or any other, network.